You cannot really do autodiff in a slow language. I mean you can but nobody wants to run large machine learning training algorithms on a slow language like Python or R.

You could write autodiff in say C++ but it is a user unfriendly language not well suited for machine learning and scientific computing.

Swift is a nicer high level language you can do autodiff in. But honestly I don’t see the point with Swift either.

Julia already does AutoDiff extremely well and outperforms Swift and pretty much everybody else.